honey that is toxic or psychoactive due to chemicals in plants or the environment

(Britain, New Zealand, informal) Completely insane.

A stock character in popular fiction; a bumbling scientist working on unlikely ways to save the world, or a villainous one bent on destroying it.

(uncountable, by ellipsis) Mad cow disease; bovine spongiform encephalopathy. / (countable) A cow afflicted with mad cow disease. / Used other than figuratively or idiomatically: see mad, cow.

(idiomatic) Extremely angry; furious to the point of outburst.

(idiomatic) A sum of money, often relatively small in amount, kept in reserve to use for impulsive, frivolous purposes.

Demented or crazy.

plural of Mad Lib

A humorously nonsensical story created from a template with blanks for certain elements. One participant supplies words to fill the blanks (e.g. "nose" where a body part is required), and the other reads the resulting story.

A rabid dog. / (figuratively, by extension) Someone who is aggressive and fanatical; an aggressor who cannot be reasoned with.